Biofilm origin of clay-coated sand grains

Wooldridge, L.J., Worden, R.H., Griffiths, J., Thompson, A. and Chung, P. (2017) Biofilm origin of clay-coated sand grains. Geology, 45(10), pp. 875-878. (doi: 10.1130/G39161.1)

Abstract

The presence of clay-sized particles and clay minerals in modern sands and ancient sandstones has long presented an interesting problem, because primary depositional processes tend to lead to physical separation of fine- and coarse-grained materials. Numerous processes have been invoked to explain the common presence of clay minerals in sandstones, including infiltration, the codeposition of flocculated muds, and bioturbation-induced sediment mixing. How and why clay minerals form as grain coats at the site of deposition remains uncertain, despite clay-coated sand grains being of paramount importance for subsequent diagenetic sandstone properties. We have identified a new biofilm mechanism that explains clay material attachment to sand grain surfaces that leads to the production of detrital clay coats. This study focuses on a modern estuary using a combination of field work, scanning electron microscopy, petrography, biomarker analysis, and Raman spectroscopy to provide evidence of the pivotal role that biofilms play in the formation of clay-coated sand grains. This study shows that within modern marginal marine systems, clay coats primarily result from adhesive biofilms. This bio-mineral interaction potentially revolutionizes the understanding of clay-coated sand grains and offers a first step to enhanced reservoir quality prediction in ancient and deeply buried sandstones.

• Item Type: Articles
• Additional Information: This work was carried out as part of the Chlorite Consortium at Liverpool University (UK), sponsored by BP, BG, Shell, Eni, Statoil, Petrobras, Woodside, and Chevron oil companies.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Chung, Mr Peter
• Authors: Wooldridge, L.J., Worden, R.H., Griffiths, J., Thompson, A., and Chung, P.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Geology
• Publisher: Geological Society of America
• ISSN: 0091-7613
• ISSN (Online): 1943-2682
• Copyright Holders: Copyright © 2017 The Authors
• First Published: First published in Geology 45(10): 875-878
• Publisher Policy: Reproduced under a Creative Commons license